• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.67-72
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• 2002

Real-time techniques are motivated by a number of factors including the potential for direct acquisition of diagnostic quality images, facilitation of patient-specific imaging parameters, and reduced examination time. Real-time MRI includes not only a rapid pulse sequence but also high speed image reconstruction and easy interactivity. The frame rate of the real-time technique used should be matched to the physiological timeframes under study. Principal applications thusfar have been in localization, fluoroscopic triggering, guidance of other processes, and potentially in the generation of diagnostic images of moving structures.

• Journal of International Society for Simulation Surgery
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• v.2 no.2
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• pp.87-89
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• 2015

Closed reduction using acrylic splints with circummandibular fixation has been known to be useful techniques in pediatric mandibular fractures. However, this technique has some shortcomings, including needs for impression taking or additional laboratory process, which can increase the exposure time of general anesthesia or make an additional sedation visit. Recently, the advancement of computer-aided maxillofacial surgery offers to clinicians to expansion of its application. This case report represents a technique of computer-assisted virtual reconstruction and computer-aided designed splint fabrication in a 2-year-old boy with mandibular body fracture.

• Journal of Information Display
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• v.3 no.3
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• pp.12-16
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• 2002

We first review a real-time three-dimensional (3-D) holographic recording technique called optical scanning holography (OSH) and discuss holographic reconstruction using spatial light modulators (SLMs). We then present how the overall system can be used for 3-D holographic television (TV) display with a wide-angle view of a 3-D image, and address some of the issues encountered. Finally, we suggest some techniques to alleviate the issues encountered in such a 3-D holographic TV system.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.281-284
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• 2002

We first review a real-time holographic recording technique called optical scanning holography (OSH) and discuss holographic reconstruction using spatial light modulators (SLMs). We then present how the overall system can be used for three-dimensional (3-D) holographic television (TV) system and address some of the issues encountered. Finally, we suggest some techniques to alleviate the issues encountered in such a 3-D holographic TV.

• Archives of Reconstructive Microsurgery
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• v.18 no.2
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• pp.62-66
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• 2009

Purpose: Despite the free tissue transfer using microsurgical technique being the current trend of soft tissue reconstruction of the hand, the pedicled groin flap has the advantage to provide coverage for the mangled hand without necessitating the use of a damaged arterial system and also providing the benefit of saving the arterial system for later free tissue transfer. This report presents the author's experience using pedicled groin flap in four cases of mangled hands with massive bone and soft tissue defects requiring later thumb reconstruction with the free wrap around flap. Materials and methods: The patients' age ranged from 30 to 51 years; three patients were male and one was female. The causes of mangled hand included two machinery crush injuries, one laboratory explosion and one motor vehicle accident. While evaluating the post-operative results, factors like flap survival, complications, stability in opposition, pinch power and 2 point discrimination were taken into account. Results: All massive soft tissue defects of the hands were completely covered with pedicled groin flap successfully. The reconstructed thumb using free wrap around flap did not have any limitation in opposition. There was no occurrence of post-operative infection and all the flaps survived completely. The average pinch power was 70% of the contralateral intact thumb and average 2 point discrimination was 10 mm. Conclusion: The pedicled groin flap for the reconstruction of the massive soft tissue defects of the hand with subsequent reconstruction of the thumb with a wrap around flap is a very useful procedure. The combined use of pedicled groin flap and wrap around flap allows adequate coverage of sizable soft tissue defects and functional thumb opposition in cases of reconstruction of the mangled hands.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.339-340
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• 2002

Natural castor oil was chemically reconstructed to extend the carbon chains by means of iso-reaction so as to improve the rheological behavior, by way of increasing the viscosity index and decreasing the pour point. The rheological and tribological characteristics of the reconstructed castor oil were comparatively investigated with those of the natural castor oil and several other vegetable oils and a mineral oil. The friction and wear test results on a four-ball machine indicate that the chemically reconstructed castor oil has considerably improved rheological and tribological properties as compared with the natural castor oil. It shows a greatly increase viscosity index and largely decreased pour point, which makes it applicable to low temperature lubrication. The chemically reconstructed castor oil even shows better tribological behavior than pentaerythritol ester or di-iso-capryl sebacate. However, it is still needed to increase the oxidation stability of the reconstructed castor oil.

• Journal of Power Electronics
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• v.16 no.2
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• pp.621-630
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• 2016

In this paper, a single current sensor technique (SCST) is proposed for single-phase full-bridge inverters. The proposed SCST measures the currents of multiple branches at the same time, and reconstructs the average inductor, capacitor, and load current in a single switching cycle. Since all of the branches' current in the LC filter and the load are obtained using the SCST, both the inductor and the capacitor current feedback schemes can be selectively applied while taking advantages of each other. This paper also analyzes both of the current feedback schemes from the view point of the closed-loop output impedance. The proposed SCST and the analysis in this paper are verified through experiments on a 3kVA single-phase uninterruptible power supply (UPS).

• ETRI Journal
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• v.36 no.3
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• pp.450-459
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• 2014

In this paper, we present a new, easy-to-generate system that is capable of creating virtual 3D tree models and simulating a variety of growth processes of a tree from a single, real tree image. We not only construct various tree models with the same trunk through our proposed digital image matting method and skeleton-based abstraction of branches, but we also animate the visual growth of the constructed 3D tree model through usage of the branch age information combined with a scaling factor. To control the simulation of a tree growth process, we consider tree-growing attributes, such as branching orders, branch width, tree size, and branch self-bending effect, at the same time. Other invisible branches and leaves are automatically attached to the tree by employing parametric branch libraries under the conventional procedural assumption of structure having a local self-similarity. Simulations with a real image confirm that our system makes it possible to achieve realistic tree models and growth processes with ease.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1495-1502
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• 2020

A new method of X-ray source spectrum estimation based on compressed sensing is proposed in this paper. The algorithm K-SVD is applied for sparse representation. Nonnegative constraints are added by modifying the L₁ reconstruction algorithm proposed by Rosset and Zhu. The estimation method is demonstrated on simulated spectra typical of mammography and CT. X-ray spectra are simulated with the Monte Carlo code Geant4. The proposed method is successfully applied to highly ill conditioned and under determined estimation problems with a good performance of suppressing noises. Results with acceptable accuracies (MSE < 5%) can be obtained with 10% Gaussian white noises added to the simulated experimental data. The biggest difference between the proposed method and the existing methods is that multiple prior knowledge of X-ray spectra can be included in one dictionary, which is meaningful for obtaining the true X-ray spectrum from the measurements.

• Geomechanics and Engineering
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• v.14 no.2
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• pp.195-202
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• 2018

Many laboratory experiments on crack propagation under uniaxial loading and biaxial loading have been conducted in the past using transparent materials such as resin, polymethyl methacrylate (PMMA), etc. However, propagation behaviors of three-dimensional (3D) cracks in rock or rock-like materials under tri-axial loading are often considerably different. In this study, a series of true tri-axial loading tests on the rock-like material with two semi-ellipse pre-existing cracks were performed in laboratory to investigate the acoustic emission (AE) characteristics and propagation characteristics of 3D crack groups influenced by intermediate principal stress. Compared with previous experiments under uniaxial loading and biaxial loading, the tests under true tri-axial loading showed that shear cracks, anti-wing cracks and secondary cracks were the main failure mechanisms, and the initiation and propagation of tensile cracks were limited. Shear cracks propagated in the direction parallel to pre-existing crack plane. With the increase of intermediate principal stress, the critical stress of crack initiation increased gradually, and secondary shear cracks may no longer coalesce in the rock bridge. Crack aperture decreased with the increase of intermediate principal stress, and the failure is dominated by shear fracturing. There are two stages of fracture development: stable propagation stage and unstable failure stage. The AE events occurred in a zone parallel to pre-existing crack plane, and the AE zone increased gradually with the increase of intermediate principal stress, eventually forming obvious shear rupture planes. This shows that shear cracks initiated and propagated in the pre-existing crack direction, forming a shear rupture plane inside the specimens. The paths of fracturing inside the specimens were observed using the Computerized Tomography (CT) scanning and reconstruction.